Top 30 C# Multiple Choice Questions (MCQs) with Answers for 2025
C# (C Sharp), developed by Microsoft, is a powerful, object-oriented programming language widely used for building robust applications on the .NET framework. Whether you’re preparing for C# interviews, certification exams, or simply sharpening your coding skills, these 30 C# MCQ questions with answers cover essential topics like data types, OOP concepts, control structures, LINQ, and more. Designed for beginners and advanced learners, this quiz will help you excel in 2025.
Why Practice C# MCQs?
- Interview Success: Master frequently asked C# questions for technical interviews at top tech companies.
- Certification Prep: Ideal for Microsoft certifications like MTA or MCSD.
- Skill Development: Strengthen your understanding of C# syntax, .NET framework, and best practices.
- Career Boost: C# is in demand for web, desktop, and game development (e.g., Unity).
C# MCQ Questions and Answers
1. C# is a:
a) General-purpose programming language
b) Scripting language
c) Markup language
d) Database query language
2. C# was developed by:
a) Oracle
b) Microsoft
c) Google
d) Apple
3. Which of the following is NOT a valid C# data type?
a) int
b) float
c) char
d) number
4. What is the output of the following code?
int x = 5; Console.WriteLine(x++);
a) 5
b) 6
c) 4
d) Error
5. The `static` keyword in C# is used to:
a) Create instance-specific members
b) Share members across all instances of a class
c) Prevent inheritance
d) Define constant values
6. Which access modifier makes a member accessible only within its own class?
a) public
b) private
c) protected
d) internal
7. In C#, the `null` value represents:
a) Zero
b) An empty string
c) No object reference
d) A default value
8. Which of the following is a value type in C#?
a) String
b) Array
c) Class
d) Int32
9. What does the `virtual` keyword allow in C#?
a) Method overriding in derived classes
b) Method overloading
c) Static method creation
d) Abstract method declaration
10. The `using` statement in C# is primarily used for:
a) Exception handling
b) Resource management
c) Importing namespaces
d) Defining classes
11. Which of the following is true about C# interfaces?
a) They can contain fields
b) They can contain implementation
c) They define a contract for classes
d) They cannot be inherited
12. What is the output of the following code?
string s = "Hello"; Console.WriteLine(s.ToUpper());
a) hello
b) HELLO
c) Hello
d) Error
13. LINQ in C# stands for:
a) Language Integrated Query
b) Language Independent Query
c) Logical Interface Query
d) Linked Integrated Query
14. Which keyword is used to define a constant in C#?
a) const
b) static
c) readonly
d) final
15. What is the base class for all C# classes?
a) System.Object
b) System.Type
c) System.Base
d) System.Class
16. Which of the following is a reference type in C#?
a) int
b) double
c) string
d) bool
17. The `try-catch` block in C# is used for:
a) Loop control
b) Exception handling
c) Memory allocation
d) File operations
18. What is the purpose of the `namespace` keyword in C#?
a) To define a class
b) To group related types
c) To declare variables
d) To handle exceptions
19. Which operator is used for type checking in C#?
a) is
b) as
c) typeof
d) cast
20. What is the output of the following code?
int[] arr = {1, 2, 3}; Console.WriteLine(arr.Length);
a) 2
b) 3
c) 4
d) Error
21. In C#, the `async` keyword is used to:
a) Define synchronous methods
b) Enable asynchronous programming
c) Prevent method execution
d) Lock resources
22. Which of the following is NOT a valid loop in C#?
a) for
b) while
c) do-while
d) foreach-while
23. The `ref` keyword in C# is used to:
a) Pass arguments by value
b) Pass arguments by reference
c) Return multiple values
d) Define constants
24. What does the `sealed` keyword do in C#?
a) Prevents method overriding
b) Prevents class inheritance
c) Locks a variable
d) Seals a namespace
25. Which collection type in C# allows key-value pairs?
a) List
b) Array
c) Dictionary
26. What is the output of the following code?
int? x = null; Console.WriteLine(x.HasValue);
a) True
b) False
c) Null
d) Error
27. The `var` keyword in C# is used for:
a) Dynamic typing
b) Implicitly typed local variables
c) Global variable declaration
d) Constant declaration
28. Which of the following is true about C# delegates?
a) They are used to define classes
b) They represent methods with a specific signature
c) They are used for file operations
d) They prevent inheritance
29. In C#, the `StringBuilder` class is used to:
a) Create immutable strings
b) Efficiently manipulate strings
c) Parse integers
d) Handle exceptions
30. What is the purpose of the `await` keyword in C#?
a) To pause execution until an asynchronous task completes
b) To start a new thread
c) To lock a resource
d) To handle exceptions
Answer Key
- a) General-purpose programming language
- b) Microsoft
- d) number
- a) 5
- b) Share members across all instances of a class
- b) private
- c) No object reference
- d) Int32
- a) Method overriding in derived classes
- c) Importing namespaces
- c) They define a contract for classes
- b) HELLO
- a) Language Integrated Query
- a) const
- a) System.Object
- c) string
- b) Exception handling
- b) To group related types
- a) is
- b) 3
- b) Enable asynchronous programming
- d) foreach-while
- b) Pass arguments by reference
- b) Prevents class inheritance
- c) Dictionary
- b) False
- b) Implicitly typed local variables
- b) They represent methods with a specific signature
- b) Efficiently manipulate strings
- a) To pause execution until an asynchronous task completes
Tips to Master C# MCQs
- Practice Consistently: Solve these C# MCQs multiple times to solidify concepts like OOP, LINQ, and asynchronous programming.
- Understand the Logic: Review the answer key and understand why each option is correct or incorrect.
- Explore Resources: Visit Microsoft Learn for tutorials or check X posts with #C# for community insights.
- Apply Knowledge: Write small C# programs to test concepts like delegates, async/await, or collections.